Apparatus for moving a well flow conductor into or out of a well



Nov. 2, 1965 P. s. SIZER 3,215,203

APPARATUS FOR MOVING A WELL FLOW CONDUCTOR INTO OR OUT OF A WELL FiledApril 17, 1961 5 Sheets-Sheet l INVENTOR Phillip S. Sizer ATTORNEYS Nov.2, 1965 P. s. SIZER APPARATUS FOR MOVING A WELL FLOW CONDUCTOR INTO OROUT OF A WELL 5 Sheets-Sheet 2 Filed April 17, 1961 hillip S. Sizer WN P/ ATTORNEYS BY W Nov. 2, 1965 P. s. SIZER 3,215,203 APPARATUS FOR MOVINGA WELL FLOW CONDUCTOR INTO OR OUT OF A WELL Filed .April 17, 1961 -5 Sheets-Sheet 4 2: 320 X 3" A k 335 340 320 i 3/ PV 33Z' 300 28 w 3n F g 235' v JIJu 337 33/ 328 320 INVENTOR Phillip S. Sizer ATTORNEYS Nov. 2,1965 P. s. SIZER 3,215,203

APPARATUS FOR MOVING A WELL FLOW CONDUCTOR INTO OR OUT OF A WELL FiledApril 17, 1961 s Sheets-Sheet 5 INVENT Phiilip S. Sizer United StatesPatent 3,215,203 APPARATUS FOR MOVING A WELL FLOW CON- DUCTOR INTO OROUT OF A WELL Phillip S. Sizer, Dallas, Tex., assignor to OtisEngineering Corporation, Dallas, Tex., a corporation of Delaware FiledApr. 17, 1961, Ser. No. 103,351 34 Claims. '(Cl. 166-77) This inventionrelates to well tools and more particularly to apparatus for moving awell flow conductor, such as a tubing string, into or out of a Well.

One object of this invention is to provide a new and improved apparatusfor moving a flow conductor into or out of a well.

An important object of the invention is to provide a new and improvedapparatus for moving a flow conductor into or out of a well through awell head against well pressure which is mounted on and entirelysupported by the well head, whereby said apparatus may be used onoffshore, on water or marine wells having no derrick or working platformin connection with the well, thus providing means for running pipe orthe like into or out of such wells without the use of a derrick or thenecessity to build a platform to support hoisting equipment and thelike.

A further object is to provide an apparatus of the character describedfor moving pipe into or out of a well wherein the apparatus is entirelysupported by the well head and is operated by fluid pressure from asource independent and external of the well.

A particular object is to provide an apparatus of the characterdescribed comprising gripping means vertically reciprocable andselectively engageable with the flow conductor, or the like, to snub thesame into or out of a well, wherein the gripping means for gripping thetubing and the means for imparting reciprocatory motion to one of saidgripping means relative to the other are energized by fluid pressuremeans, and wherein the force applied to the gripping means to move theconductor is laterally balanced longitudinally of the apparatus and theconductor being moved thereby.

A still further object is to provide apparatus arranged to be mounted onand supported solely by a wellhead for controlling the movement oftubing in a well, which includes an assembly of hydraulically operatedblowout preventers for preventing the escape of fluids between thetubing and the well casing and a plurality of hydraulically operatedpipe gripping assemblies, each selectively operable to engage thetubing, and wherein hydraulic fluid pressure operated means is providedfor moving one of the pipe gripping assemblies reciprocablylongitudinally relative to the other to lower or raise the tubing in thewell.

A still further object is to provide an apparatus for moving or snubbinga flow conductor, such as a tubing, into or out of a well against fluidpressure within the well having a tubing handling means for positioninga stand of tubing within the tubing moving apparatus or for removing thetubing therefrom, and wherein both the moving apparatus and the handlingmeans are entirely mounted on and supported by the wellhead.

A still further object is to provide a slip type gripping assembly foruse with snubbing apparatus wherein the slips are moved by hydraulic orfluid pressure between inoperative or non-gripping positions andoperative tubing gripping position, and wherein said gripping slips maybe held in such operative gripping position by mechanical locking mean-sindependently of the maintenance of the hydraulic or fluid pressure.

A still further object is to provide a new and improved hydraulicallyoperated slip type pipe gripping assembly for use with well flowconductor snugging apparatus.

Another object is to provide a new and improved hydraulic system forcontrolling the action of the hydraulic fluid pressure operated pistonand cylinder operating means for operating the movable gripping means ofthe snubbing apparatus.

Still another particular object is to provide a fluid pressure controlsystem for controlling the movement of the snubbing piston in a snubbingapparatus of the character described wherein safety means is providedfor automatically maintaining the pressure in the cylinder on 0ppositesides of the piston of the operating means for moving the travelingsnubber to automatically lock the piston and the traveling snubberconnected therewith against movement with the well pipe in the event ofa pressure failure in the fluid pressure system.

Additional objects and advantages of the invention will be readilyapparent from the reading of the following description of a device andsystem constructed and operating in accordance with the invention, andreference to the accompanying drawings thereof, wherein:

FIGURE 1A is a view in elevation of the lower portions of an apparatusembodying the invention and related equipment mounted on a wellhead ofan oif-shore well;

FIGURE 13 is a view similar to FIGURE 1A, being a continuation thereof,showing upper portions of the apparatus;

FIGURE 2 is a schematic vertical sectional view of the gripping and thesealing assemblies of the apparatus of FIGURE 1A, showing thearrangement of the same when forcing tubing into the well against wellpressure;

FIGURE 3 is a view similar to FIGURE 2 showing the arrangement of thegripping and sealing assemblies while holding the tubing against wellpressures as the traveling snubber or gripping member is being movedupwardly to take another grip on the tubing;

FIGURE 4 is a view similar to FIGURE 2 showing the arrangement of thegripping and sealing assemblies during lowering of the tubing into thewell when the weight of the tubing exceeds well pressure;

FIGURE 5 is a view similar to FIGURE 4 howing the tubing supportedmomentarily by the stationary snubber or gripping member while thetraveling snubber of the gripping assembly is being moved upwardly toposition to again support and lower the tubing;

FIGURE 6 is a schematic view of the apparatus and a hydraulic system foroperating and controlling the same;

FIGURE 7A is a schematic sectional view of a fourway valve forcontrolling a vertically movable piston of the apparatus showing thevalve in position to cause the piston to move downwardly;

FIGURE 7B is a view similar to FIGURE 7A showing the valve positioned tocause upward movement of the piston;

FIGURE 7C is a view similar to FIGURE 7A showing the valve moved toposition to prevent actuation of the piston in either direction;

FIGURE 8 is a view, partly in elevation and partly in section, with someparts broken away, showing the two lower or stationary gripping slipassemblies comprising the stationary snubber of gripping member of theapparatus;

FIGURE 9 is a cross-sectional view taken along the line 99 of FIGURE 8;

FIGURE 10 is a fragmentary cross-sectional view similar to FIGURE 9 butshowing the slips in retracted position;

FIGURE 11 is a top view of the slips and inserts of the upper assemblyillustrated in FIGURE 8;

FIGURE 12 is a schematic view of a modified form of hydraulic system foroperating and controlling the movement of the snubbing apparatusembodying the invention, illustrating the operation of the system formoving the snubbing piston downwardly;

FIGURE 13 is a similar schematic view of the hydraulic system of FIGURE12, illustrating the operation of the system for moving the snubbingpiston upwardly;

FIGURE 14 is a schematic view of a modified form of hydraulic system forcontrolling the operation of the slip assemblies and the blowoutpreventer system;

1 FIGURE 15 is an enlarged view of one of the snubbers of the grippingassemblies showing portions thereof in section;

FIGURE 16 is a view of the snubber of FIGURE 15 taken to one side atright angles to FIGURE 15;

FIGURE 17 is a fragmentary sectional View of the snubber operatinglinkage and piston connections taken on the line 17-17 of FIGURE 16; and

FIGURE 18 is an exploded view of the hydraulic operating cylinder andpiston assembly and lever mechanism for operating the snubber of FIGURE16.

Referring to FIGURES 1A and 1B of the drawings, one apparatus embodyingthe invention is shown in use with a well 10, located in a body of water11. The well has the usual well casing 13 which extends above aprotective caisson 14 and is connected at its upper end to the Christmastree control assembly or to the wellhead 15, and is protected againstcollision with floating debris or surface craft by a cribbing 12,constructed of piling and timbers.

The apparatus embodying the invention is adapted for use on such marineor offshore wells having no derricks or platforms for supportinghoisting equipment and the like, and hence is designed to be mounted onthe wellhead and entirely supported thereby. The apparatus includes amaster valve 16 which is secured to the upper end of the wellhead withthe axial bore of the valve in I axial alignment with the bore of thecasing. The valve is provided for the purpose of shutting or closing 01fthe upper end of the bore of the casing when no tubing extends throughthe valve. Annular laterally-directed flanges 16a and 16b on the lowerand upper faces of the valve housing have bolts, or other suitablefastening means, extending through suitable apertures of the flanges tosecure the valve body to the wellhead and to elements of the apparatuslocated above the valve.

7 Mounted above the valve 16 in vertical upward succession are a spool17, a safety blowout preventer 18, a lower operating blowout preventer19, a spool 20, and an upper operating blowout preventer 21. Each ofthese elements is provided with external annular flanges at its upperand lower ends for connecting it to elements above and below the same.The blowout preventers are of a conventional type which are operated byfluid pressure and each has a vertical flow passage axially aligned withthe bore of the casing. The preventers, which are used to retainpressure within the casing when a length of tubing is being passedtherethrough, may be actuated to close off the annular space around thetubing to prevent the well from blowing out, i.e., the fluid pressureescaping from the well, even though the vertical passage above thepreventers is open to the atmosphere. It is to be understood, of course,that the tubing is plugged to prevent the well from blowing outtherethrough. When in their operational tubing engaging position, thepreventers do not preclude longitudinal movement of the tubing althoughmanipulation of the preventers is required to move the tubing couplingstherepast.

Above the uppermost blowout preventer 21 are mounted in vertical upwardsuccession a stripper 22, a spacer spool 23, and slip assemblies 24 and25 comprising a lower stationary snubber means 26, each of which isprovided at its ends with annular flanges for facilitating connectionthereof to elements above and below and with a flow passage axiallyalignable with the bore of the well casing. The stripper which isconnected to the blowout preventer 21 has essentially a highly resilientannular packoff and acts as a seal member for low pressures and as awiper means for the tubing as it moves upwardly therethrough. Because ofits resilience, it has the particular advantage of allowing passage oftubing couplings without requiring its manipulation. The slip assemblies24 and 25, which are installed above the spool 23 and inverted withrespect to one another, constitute the lower or stationary snubber meansused to engage the well tubing to prevent its longitudinal movementtherepast. One of the slip assemblies is adapted to prevent the tubingfrom being blown or expelled upwardly from the well by fluid pressurewithin the well, while the other assembly is adapted to support thetubing to prevent it from falling into the well due to gravity. When aparticular slip assembly is functionally employed, of course, isdetermined by the relation of the well pressure to the total weight oftubing.

A pistol and cylinder assembly or travelling snubber operating means 27,mounted above the slip assembly 25, carries an upper or travellingsnubber 40 and with it controls the raising and lowering of tubing intoor from the well casing through the wellhead. The operating meansassembly includes an outer cylinder 28, provided with annular flanges atits ends for connecting it to elements above and below the cylinder, andan inner cylinder 29 mounted concentrically in the outer cylinder and ofequal length therewith. The cylinder assembly is mounted on a spool 30interposed between said assembly and the slip assembly or stationarysnubber 26. An annular piston 31, shown in FIGURES 2 through 5, isslidably mounted in the annular cylinder formed between the concentricouter and inner cylinders and is secured to the lower end of a tubularpiston rod 32 which extends upwardly from the piston between the innerand outer cylinders and upwardly beyond the upper ends thereof. Asuitable seal 33, such as a packing gland or the like, is attached tothe upper end of the inner wall of the outer cylinde 28 to provide afluid-tight seal between the tubular piston rod and the outer cylinder.The annular space between the cylinders 28 and 29 is closed at theirlower ends by a transverse annular end member 33a which defines, withthe cylinders and the piston 31, a lower fluid-tight chamber 35. Sincethe outer cylinder 28, the piston rod 32, the seal 33 and piston 31define an upper fluid-tight annular chamber 36 above the piston, it isapparent that the piston can be readily moved upwardly by introducingfluid under pressure from a suitable supply of fluid into the lowerannular chamber 35 below the piston, or that it can be moved downwardlyby applying fluid pressure in the upper chamber 36 above the piston,provided, of course, that fluid is permitted to escape from the chamberon the side of the piston opposite that to which the pressure is beingapplied.

.A third slip assembly, identical in construction to each of the slipassemblies 24 and 25, comprises the upper or travelling snubber 40 andis secured to the upper end of the tubular piston rod 32, so as to beraised and lowered by longitudinal movements of the piston rod. When theslip assembly of the snubber 40 is inverted with its slips oriented asillustrated in FIGURES 2 and 3, the slips may be actuated to grip alength of tubing which extends coaxially through the concentriccylinders, and by controlled application of hydraulic pressures in thechambers on eithe side of the piston to move the piston downwardly, willforc the tubing into the well against the force of well pressure. Thelower stationary snubber or slip assembly 26 is employed to hold thetubing during the upstroke of the piston, the travelling snubberassembly 40 being disengaged from the tubing and moved upwardly with thepiston and piston rod relative to the tubing.

To limit deflection of the tubing under large compressive loads atubular guide 255a may also be provided to increase the range of wellpressures over which the apparatus is operable. The guide, of course,should be mounted co-axially with the inner cylinder 25! in any suitablemanner.

When the weight of tubing is suflicient to overcome the force of wellpressure, the upper slip assembly or travelling snubber 40 is orientedas illustrated in FIGURES 4 and 5. In this position the slip assemblysupports the tubing as it is lowered by downward movement of the pistoneffected by suitable application of fluid pressures on either side ofthe piston of the snubber operating means. In this particularrelationship of well pressure and tubing weight, the slip assembly 24 ofthe lower stationary snubber is employed to hold the tubing againstdownward movement while the travelling snubber 40 is moved upwardlyrelative to the tubing to engage the tubing at a higher point thereon.

Thus, it will be seen that the slip assembly of the travelling snubber40 is used cooperatively with either the slip assembly 24 or 25 of thestationary snubber, depending on the relationship of tubing weight andwell pressure. Of course, occasionally it may be desired to engage thtubing with all of the slip assemblies simultaneously to preventlongitudinal movement of the tubing in either direction, especially aswhen the above mentioned conditions may be expected to vary suddenly andwithout notice.

The mechanism for lifting and lowering the lengths of tubing which arelowered into and lifted out of the cylinder assembly is also itselfsupported by the wellhead and the equipment thereabove and comprises amast or gin pole 41 held in vertical position by clamps 42 and 43attached to the stripper 22 and the spool 30, respectively. The gin poleis provided with a reel 44 and pulley 45 attached thereto by laterallyextending brackets 46 and 47, respectively. A cable 48, spooled on thereel and reeved about the pulley is equipped with a hook 49 at its freeend for the attachment of bails (not shown), or the like, for engagingsingle lengths of tubing, whereby the tubing lengths may be easilylifted or lowered by operation of the cable reel.

For the purpose of supporting personnel and control equipment, such as avalue control panel, or the like, a horizontal platform 51 is disposedadjacent the upper end of the piston and cylinder assembly 27 andfastened to the wellhead supported equipment by a plurality of braces52. The braces are arranged with their lower ends spacedcircumferentially around the piston and cylinder assembly 27 and securedto the spool 30 in any suitable manner, as by welding, and with theirupper ends supporting and secured to the platform by any suitable means.Apertures 51a and 511) are provided in the platform for accommodatingthe piston and cylinder assembly and gin pole which extend therethrough.The platform has a railing 53 supported by stanchions 54. The cable reelon the gin pole is located at a convenient height above the platform soas to be easily operated by a person standing on the platform.

Racks may be provided on some auxiliary structure, such as a barge orthe like, which is preferably independent of the well or its cribbing,for holding the tubing which is to be inserted in or removed from thewell. In addition, the rack supporting structure may also contain thehydraulic pump and its prime mover or power plant for supplying fluidpressure to the piston and cylinder assembly. The connections betweenthe pressure supply and the piston and cylinder assembly 27 must besufiiciently flexible and of ample length to accommodate any movementsbetween the immovable wellhead and the auxiliary structure.

When it is desired to force or snub tubing into the well, the apparatusis arranged as illustrated in FIGURES 2 and 3. The master gate valve 16is moved to the open position illustrated in FIGURE 2 and the tubingstring T, which comprises a plurality of lengths of tubing, fastenedtogether by a coupling C, extends through the master gate valve and thewell-head 15 into the well casing. The blowout preventer 21 is firstmoved to closed position to seal around the tubing and prevent the wellfrom blowing out while the blowout preventers 19 and 18 are initiallyopen. The upper travelling snubber 40 is moved into gripping engagementwith the tubing and the slip assemblies 24 and 25 of the stationarysnubber are moved to open position wherein they are disengaged from thetubing to permit the same to be moved downwardly therethrough. Fluidunder pressure is introduced into the chamber 36 through a port 36b tocause the piston 31 to move downwardly as fluid is permitted to escapethrough the .port 35b from the chamber 35 below the piston. Thetravelling snubber :being connected to the piston by the tubular pistonrod 32, downward movement of the piston and tubular piston rod nowcauses the tubing string to move downward-1y into the well against thepressure there- 1n.

In order to provide positive control of the pipe movement, the escaperate of fluid from the lower chamber 35 through the port 3512 iscontrolled to apply a back pressure in the lower chamber acting upwardlyagainst the piston. Such control also provides for prompt cessation ofdownward movement of the tubing to preclude the possibility of equipmentdamage should the lower end of the tubing encounter resistance in thecasing, such as a sand bridge or a point of decreased internal diameterof the casing. By bleeding fluid from beneath the piston and at the sametime keeping the chamber 36 above the piston filled with fluid toexclude air, a suflicient back pressure is maintained to permit thetubing to move slowly into the well.

When the coupling C has been moved downwardly to a point just above theupper operating blowout preventer 21, the lower operating blowoutpreventer 19 is closed and the upper blowout preventer 21 is opened topermit downward movement of the coupling therepast to the position shownin FIGURE 3, whereupon the upper blowout preventer 21 is again closedand the lower operating blow-out preventer 19 opened to permit thecoupling to pass on into the well. At the end of the pistons downstroke,the slip assembly 25 of the stationary snubber is actuated to grip thetubing and the slip assembly of the upper travelling snubber 40 issubsequently disengaged from gripping engagement with the tubing, as isillustrated in FIGURE 3. The slip assembly 25 of the stationary snubberthus serves to hold the tubing against upward movement from the wellwhile the piston of the operating means 27 is being returned to itsuppermost position. At the end of the piston upstroke, the slip assemblyof the travelling snubber 40 is actuated to gripping engagement with thetubing, and the slip assembly 25 of the stationary snubber 26 disengagedtherefrom, so that the operating means 27 may once again be operated tocause the piston 31 to be forced downwardly to .move the tubing furtherdownwardly into the well against the force exerted by well pressure. Anadditional length of tubing is coupled to the string after a length ofthe tubing has been forced into the well. By repeating the foregoingsequence of operations, any desired length of tubing may be readily runinto the well until the weight of the tubing alone causes it to tend tomove downwardly in the well, i.e., until the tubing weigh-t becomes sogreat that the Well pressure acting upon the cross-sectional area ofsuch tubing is no longer sufiicient to expel or blowout the tubingstring from the Well.

When the tubing becomes sufficiently heavy to move downwardly by its ownweight, overcoming not only well pressure but also the friction ofsealing elements of the blowout preventer, the slip assembly of thetraveling snubber 40 is removed, inverted, and reinstalled in theposition illustrated in FIGURE 4, with slips wedging downwardly andinwardly.- The tubing T is then supported against falling or downwardmovement by the gripping engagement of the slips of the assembly withthe tubing, whereby such tubing may be lowered int-o the wellthrough-the closed upper operating blowout preventer 21. Just before theend of the down-stroke of the the operating means 27 is reached, theslip assembly 24 of the stationary snubber is engaged with the tubingand the weight of the tubing string is thus transferred to the lowerstationary snubber, whereupon the slip assembly of the upper travelingsnubber is disengaged from the tubing as illustrated in FIGURE 5. Thepiston and tubular piston rod 32 are then moved upwardly while thestationary snubber 26 supports the tubing string and, just before theupper end of the stroke is reached, the slip assembly of the travelingsnubber is moved to gripping engagement with the tubing string and saidtubing string is lifted to permit the ready disengagement of slipassembly 24 of the stationary snubber therefrom. This sequence ofoperation can then be repeated to lower the tubing further into thewell, the couplings connecting succeeding lengths of tubing being passedthrough the operating blowout preventers in the manner previouslydescribed, by closing the lower preventer, opening the upper preventer,moving the coupling past said upper preventer, reclosing the upper andopening the lower preventer. The lowermost or safety blowout preventer18 is used for sealing ofi varound the tubing in case of emergenciessuch as failure of either of the operating preventers or to permitreplacement of the seal elements of such operating preventers.

By reversing the procedure described above, the apparatus can be used toremove the tubing from the well. During such removal, while the weightof the tubing string is suflicient to unbalance the well pressure actingon the cross sectional area of the tubing, the tubing string is liftedby the traveling snubber 40 with the slip assembly in the position shownin FIGURES 4 and 5, and by introducing hydraulic fluid under pressureinto the chamber 35 below the piston 31 of the snubber operating means27 while releasing fluid pressure from the upper chamber 36. Whenremoving tubing while the well pressure is suflicient to expel it fromthe well, the rate of upward movement is positively controlled by slowlyreleasing or bleeding the fluid from the upper chamber 36 above thepiston. The tubing, of course, can move only as fast as the releasing orbleeding of fluid is permitted to take place. The annular chamber 37between the tubular piston rod and the inner cylinder 29 is vented atits upper end, to permit fluid to escape or enter by the loose fitprovided between the piston rod and the annular guide bushing 38 mountedon the upper end of said inner cylinder.

One form of hydraulic system which may be used to actuate the piston 31is illustrated schematically with the snubbing and sealing apparatus inFIGURE 6. The entire liquid circuit represented in the system is filledwit-h a substantially incompressible fluid, such as common hydraulicfluid, and a supply of the fluid is contained in the reservoir or tank101. A constant delivery pump 102, which may be of any suitable typereadily available on the market and powered by a suitable motor, picksup fluid from the reservoir through the conduit 103 and discharges thefluid through the conduit 104 at a greatly increased pressure. The fluidunder pressure from the pump 102 is delivered through a check valve 105and a conduit 106 to a 4-way valve 109 for controlling the admission ofthe fluid to the chambers on either side of the piston.

Connecting with the conduit 106 through a conduit 107a is an accumulator107 for storing a volume of fluid under pressure. Should the pump or itsprime mover fail, the capacity of the accumulator is suflicient toactuate at least several of the slip assemblies and blowout preventersso that the tubing may be held against movement relative to thewellhead, and escape of fluid pressure from the well may be preventeduntil the pump or prime mover is again rendered operative. In addition,a pressure relief valve 108 is connected in fluid communication with theconduit 106 and the reservoir through the conduits 108a and 108b,respectively. The pressure relief valve is set to open at apredetermined pressure, which occurs after the accumulator has beencharged and there is no demand for power fluid, to discharge fluid fromthe pump into the reservoir and prevent excessive pressures in thesystem while permitting continuous operation of the pump.

The manner in which the 4-way valve 109 controls the application offluid pressure to the piston and cylinder assembly of the operatingmeans 26 is illustrated in FIG- URES 7A, 7B, and 7C.

When the valve is in the position shown in FIGURE 7A, the piston ismoved upwardly. Fluid under pressure enters from the conduit 106 andpasses through the passageway 110 into the conduit 111 which conductsthe pressure fluid through the port 3512 into the chamber 35 below thepiston. As the piston is moved upwardly by the increased pressure in thelower chamber, fluid in the upper chamber 36 above the piston isexpelled and returned to the reservoir 101 through the port 36b, conduit112 and passageway 113 of the valve into the conduit 114 which connectswith the reservoir through the communicating conduits 115 and 116.

. When in the position shown in FIGURE 7B, fluid under pressure from theconduit 106 is delivered through the valve passage 113 into the conduit112 which conducts the fluid through the port 36b into the chamber 36above the piston. As the piston is moved downwardly by the increasedpressure in the chamber above the piston, fluid in the chamber below thepiston is released or expelled through the opening 35b, conduit 111,valve passage 110, communicating conduits 114, 115 and 116, into thereservoir 101.

When the valve is positioned as shown in FIGURE 7C, no flow can takeplace through the valve since all its passages are closed. In thisposition of the valve, the substantially incompressible hydraulic fluidis trapped in both of the chambers on opposite sides of the piston andthe piston can neither move up nor down, but remains locked in whateverposition it may be when the valve is closed.

Pressure fluid from the conduit 106 is also delivered at a reducedpressure to 4-way valves 124, 125, and 126, which control the operationof the slip assembly of the traveling snubber 40, and the slipassemblies 25 and 24 of the stationary snubber, respectively, and to4-way valves 127, 128, and 129 which control the operation of theblow-out preventers 21, 19 and 18, respectively. The fluid underpressure in the conduit 106 is delivered by means of a conduit to andthrough an adjustable reducing valve 121 to be discharged at apredetermined reduced pressure to the conduit 122 and thence to adistributing conduit 123 which conducts the fluid to the slip assemblyand blowout preventer control valves. These control valves aresubstantially the same as the 4-way valve 109 but operated by movementto only two control positions, similar to the valve positions shown inFIG- URES 7A and 7B, which determine whether the particular slipassembly or blow-out preventer controlled thereby is in operative tubeengaging position or in inoperative position.

When the valve 127 is in one of its two positions fluid under pressureis conducted to the upper operating blowout preventer 21 through theconduit 130 to actuate the hydraulically operated sealing elements ofsuch blowout preventer to tubing engaging position, as illustrated inFIGURE 3. Fluid expelled from the hydraulic cylinder associated with thepreventer is returned to the reservoir through the conduit 131, thevalve 127 and conduits 115 and 116. When the valve is moved to the otherof its positions, the conduit 131 is supplied with fluid under pressurefrom the distribution line 123, and the conduit 130 is connected to theconduit 115 through the valve, thus reversing the hydraulic action ofthe blowout preventer to cause the seal elements to be disengaged fromthe tubing.

In similar manner, the valves 128 and 129 many be manipulated to controlthe lower operating blowout preventer 19 and the safety blowoutpreventer 18, respectively; and, the valves 124, and 126 may likewise beemployed to control the operation of the slip assemblies.

Controls which are presently available on the market could be installedin the conduits 111, 112, and 114 to control the action of the pistonmore closely as to force and speed. For instance, such controls couldcause the piston to move the tubing into or out of the well with onlyslight force but to cause it to move fairly rapidly on the returnstroke. This would, in most cases, be desirable since the piston wouldreadily stop should the lower end of the tubing encounter an obstructionin the well bore, thereby preventing damage to the tubing and equipment.It would also be desirable to spring load the valve 109 so that it wouldalways be in the closed or fluid blocking position shown in FIGURE 7Cunless manually held out of that position. The provision of such abiasing means would insure that the tubing would be moved only asintended by the operator.

A modified form of hydraulic system for controlling the reciprocalmovements of the piston 31 of the traveling snubber operating means 27is illustrated in FIGURES 12 and 13 and represents a preferred hydrauliccontrol system to be employed witht the snubbing apparatus describedtherein.

The system, which is filled throughout with hydraulic fluid, includes areversible hydraulic pump 300, which may be of the cross center servocontrol of swash plate type, for producing hydraulic pressure of adesired high value throughout the system. The pump, which produces fluidpressure of the order of two thousand (2000 lbs. per sq. in.) pounds persquare inch, and constitutes the principal power source of the system,is adapted to be operated by a servo control mechanism so that thedirection of output of fluid from the pump can be readily reversed.

In the operation of the system for moving the snubber operating meanspiston downwardly, and which is schematically illustrated in FIGURE 12,fluid under pressure from pump 300 is delivered through the conduits 301and 302 to the port 36b of the outer cylinder 28, thereby introducingfluid pressure into the chamber above the piston and tending to move thepiston downwardly. A by-pass check valve 303 in the conduit 301 preventsreverse flow of fluid in the conduit.

A direct operating remotely controlled counterbalance valve 305, whichis spring loaded to normally closed position, is connected on its inletside by a conduit 310 to the lower cylinder port 35b and on its outletside by a conduit 311 with the low pressure side of the pump 300. Aby-pass check valve 307 is connected between the conduits 310 and 311 toprevent back flow from the conduit 310 to the conduit 311. Thecounterbalance valve is opened by fluid pressure conducted thereto fromthe conduit 301 by the branch conduit 306 connecting the two.

The valve is designed to open in response to fluid pressures appliedthereto from the conduit 306 in excess of a predetermined value,normally 200 to 250 lbs. per sq. in. and, when so opened, permits fluidto be released or drain from the chamber 35 beneath the piston throughthe cylinder port 35b and conduits 310 and 311 to return to the lowpressure side of the pump 300. The piston 31 may thus move downwardly inthe cylinder 28 of the traveling snubber operating means 27.

Since the annular cross-sectional area of the lower chamber 35 below thepiston 31 is greater than the annular cross-sectional area of the upperchamber 36 thereabove, downward movement of the piston and the pistonrod connected therewith expels or ejects more fluid from the lowerchamber than can be admitted to the upper chamber above the piston.Hence, an excess flow line 312 is provided to conduct the excess offluid from the return line 311 through a separate path to a fluidreservoir or tank 320. The excess flow line 312 is connected at one endwith the return flow line 311 and conducts excess flow therefrom to afluid pressure pilot operated four-way spool valve 313, thence through aconductor 314 into a cooling circuit 317 which communicates with thereser-.

voir 320. A branch conduit 318 also connects the supply feed conduit 301with the pilot operated four-way spool valve 313 for effecting controlof the operation thereof and for other purposes to be hereinafterexplained. The pressures from the two lines 312 and 318 are directed toand act upon opposing hydraulic operators or diaphragms, or the like, tomove the valve in accordance with the imbalance of the pressures in thetwo lines. Thus, the valve 313 always provides for direct communicationbetween the conductor 314 and the excess flow line 312 or the branchconduit 318, whichever of the latter two contains the lower pressure.When the pressure in the feed line 301 and branch line 318 is highrelative to the pressure in the line 312, the valve 313 is moved to theposition shown in FIGURE 12, which permits the excess fluid forced outof the lower chamber 35 to pass through such valve and through theconductor 314 into the cooling circuit 317 and thence to the reservoir320. Conversely, during the upstroke of the piston 31 (shown in FIG- URE13), the pressure in the excess flow line 312 is greater than that inthe branch conduit 318 and these pressures acting on the valve 313 shiftthe valve auto matically to connect the branch conduit 318 with theconductor 314, as shown in FIGURE 13. In this position of the valve,fluid may flow from the cooling circuit 317 into the branch conduit 318,and thence through the conduit 301 to the pump 300, where suchadditional fluid from the cooling circuit makes up the shortage of fluidin the operating circuit resulting from the larger volume. of fluidintroduced into the lower chamber 35 as com pared with the smallervolume of fluid displaced from the upper chamber 36 by upward movementof the piston 31.

The cooling and circulating circuit 317 comprises the reservoir 320, acirculating pump 321 which picks up fluid from the reservoir andcirculates it from the outlet side through a conduit 322 and a checkvalve 323 to the point of connection with the conduit 314, and thencethrough a check valve 324 and a conduit 325 to a heat exchanger 326,which cools or controls the temperature of the hy draulic fluid beingcirculated and maintained in the reservoir 320, and thence through afilter 327 back to the reservoir. The check valves 323 and 324 are eachspring loaded and maintain predetermined back pressures upstream thereofin the conduits 322 and 314. The check valve 323 is preferably set tomaintain a pressure differential of approximately lbs. per sq. in.thereacross, while the check valve 324 is preferably set to maintain adifferential of approximately 60 lbs. per sq. in. across it, so that thefluid pressure in the conduit 322 between the pump 321 and the checkvalve 323 will be approximately lbs. per sq. in., while the pressurebetween the check valves 323 and 324 and in the conductor 314 will beapproximately 60 lbs. per sq. in.

A branch conduit 328 conducts fluid from the conduit 322 to across-connecting conduit 330 which connects the feed line or conduit 301with the return conduit 311. Opposed check valves 331 and 332 aredisposed in the conduit 330 on opposite sides of the connection of thebranch conduit 328 therewith, so that fluids from said branch conduitcan be directed in either direction to either of the conduits 301 or311, but so that fluid from those conduits cannot flow back through theconduit 328 to the cooling and circulating system 317. This arrangementprovides additional means for supplying hydraulic fluid to the operatingcircuit in the event the volume thereof is diminished for any reason andis particularly used in the operation of the circuit for moving thepiston 31 of the traveling snubber operating means upwardly, as will behereinafter more fully described.

A second cross feeding conduit 335 connects the feed line or conduit 301with the return line or conduit 311, and a relief conduit 336 isconnected at one end with said cross feeding conduit between a pair ofopposed check valves 337 and 338, whereby hydraulic fluid from either ofthe conduits 301 and 311 may pass said check valves to the reliefconduit 336 but cannot flow back from the relief conduit to the conduits301 and 311. The relief conduit connects at its other end with anadjustable resiliently loaded relief valve 340 whereby fluid underpressure in the relief line 336 may open said relief valve in the eventpressure in the relief line or the conduits communicating therewithexceeds a predetermined value, to permit the hydraulic fluid to passthrough the valve and an exhaust or dump conduit 341 to the reservoir320. This prevents overloading and rupturing any of the lines or valvesof the system. If desired, the dump conduit 341 could be connected tothe branch conduit 328 so as to deliver the fluid from the relief valve340 to the cooling and circulating circuit 317, where the fluid wouldpass through the heat exchanger 326 and may thus be cooled and filteredto prevent overheating.

Pressure gauges G, G and G" may be connected in the system at variouspoints to indicate the operating pressures therein at such points, asclearly shown in the drawings.

Operation of the system for causing the operating means 27 to move thetraveling snubber upwardly is schematically illustrated in FIGURE 13.For this purpose, the direction of flow of fluid under pressure from thepump 300 is reversed, by operation of the servo mechanism controllingthe vane of the pump in the usual manner, so that the pressure from thepump is delivered in the opposite direction, as shown by the arrow, todeliver high pressure through the conduit 311 past the check valve 307and through the conduit 310 to the cylinder port 351) in the lowerportion of the cylinder 28, whereby fluid under pressure is introducedinto the chamber 35 below the piston 31 and forces the piston upwardly.

A direct operating remotely controlled counterbalance valve 345 isconnected on one side to the conduit 302 and on its other side by anexhaust conduit 347 to the conduit 301 beyond the check valve 303, andhas an operating conduit 346 connected therewith for conducting pressurefrom the conduit line 311 to the valve to operate the same. When thepressure in the line 311 and conduit; 346 attains a predetermined value,substantially the same as that which opens the valve 305, and thus ofthe order of 220 to 250 lbs. per square inch, the valve 345 is moved toan open position to permit the fluid from the upper chamber 36 to passoutwardly through the upper port 36b to the conduit 302 and through thevalve 345 and the conduit 347 to the conduit 301, and thence to the pump300. Check valve 303 directs all fluid exhausted from the chamber 36through the valve 345. Fluid in the line 301 returned to the pump isagain placed under pressure and is directed into the conduit 311.

As the piston 31 is moved upwardly in the cylinder 28 of the operatingmeans, it will be apparent that a greater amount of fluid must beintroduced into the chamber 35 below the piston than is expelled orexhausted from the chamber 36 thereabove, due to the difference incrosssectional area of the two chambers. Hence, supplemental fluid isdelivered into the conduit 301 from the cooling and circulating system317 for delivery to the low pressure side of the pump 300. The branchconduit 328 leading from the conduit 322 will conduct fluid from thecooling circuit to the conduit 330 between the check valves 331 and 332.Since the higher pressure from the conduit 311 is applied to the checkvalve 332, the lower pressure fluid introduced into the conduit 330 willpass through the check valve 331 and into the conduit 301 forsupplementing the volume of hydraulic fluid delivered to the pump 300.Pressure in the cooling and circulating circuit 317 is maintained at avalue in excess of the pressure which is to be found in the conduit 301,so that hydraulic fluid will always be supplied from the circulatingcircuit through the conduits 328 and 330 to the conduit 301 whenrequired. Supplemental fluid may also move from the cooling circuit 317into the conduit 301 by way of the conductor 314, the spool valve 313and the branch conduit 318 in cases where the demand is sufficientlygreat and the valve 313 is opened by the low pressure in the conduit 318as compared with the pressure in the line 312 as has been explained.

Other elements in the hydraulic control system operate in the samemanner as previously described. However, the valve 305 will remainclosed, since the pressure in the conduit 306 is not adequate to openthe same, and all hydraulic fluid in the line 311 will be directedthrough the check valve 307 and the conduit 310 into the chamber 35.

' It will thus be seen that the hydraulic system disclosed in FIGURES 12and 13 provides a sensitive control means for accurately and positivelycontrolling movement of the snubbing piston.

In the event of a break or pressure failure in the system between thecounterbalance valves 305 and 345 and the pump, the pressure in theconduits 306 and 346 will fall below that required to open thecounterbalance valves 305 and 345 and thus those valves would remainclosed to prevent flow of hydraulic fluid therethrough outwardly fromthe chambers 35 and 36. Simultaneously, the check valves 303 and 307will prevent out-flow of fluids from either of the chambers 36 or 35 tothe conduits 301 or 311, and the hydraulic fluid would thus be trappedin the two chambers and prevent any movement of the piston 31 therein.It will therefore be seen that this modified system provides a safetyfeature for automatically hydraulically locking the piston againstmovement in the event of failure or reduction of hydraulic fluidpressure or breakage of the hydraulic fluid conduits of the system, orfailure of any of the valves in the system other than the counterbalancevalves and the check valves 303 and 307.

It is important to note that the reversible hydraulic pump 300 has aconstant load pressure of approximately lbs. per sq. in, applied to itsinlet side at all times, such fluid pressure being applied from thecooling and circulating circuit 317 by way of the branch conduit 328 andthe cross connecting conduit 330. When the circuit is operating in themanner shown in FIGURE 12, the fluid pressure from the circulatingcircuit passes through the branch conduit 323 to the cross connectingconduit 330 and thence past the check valve 332 to the return conduit311 where it acts on the inlet side of the pump. When the pump isoperating in the manner shown in FIGURE 13, the pressure fluid from thecirculating circuit is delivered from the branch conduit 328 to thecross connecting conduit 330 and flows thence through the check valve331 to the conduit 301 for supplying the elevated pressure load to theinlet side of the pump 300. This arrangement prevents entry of air intothe system and aids in supplying a suflicient volume of pressure fluidfrom the pump into the operating circuit, and is an important feature ofthe system.

It will be noted also that the network of conduits forming the hydraulicsystem provides means whereby any sudden surge of fluid pressure in anypart of the circuit may be relieved by several different paths toprotect the system against breaks resulting from the high pressure. Forexample, while the system is being operated in the manner illustrated inFIGURE 12, should a high pressure surge occur in the conduit 311 for anyreason, as might occur if the conduit became plugged near the pump 300,the surge due to the momentum of the hydraulic fluid could be relievedby sending the fluid to the reservoir 320 through the excess flow line312, the valve 313, the conductor 314 and the cooling circuit 317; or,the fluid could be directed through the conduit 335, the conduit 336,the relief valve 340 and the exhaust conduit 341 to the reservoir.

On the other hand, should a large demand be suddenly placed upon thecircuit for any reason, there could be a tendency to cause a vacuum orto draw air into the system, creating a dangerous and unsatisfactorycondition. If such a large demand did occur in the conduit 311, fluidcould enter such conduit not only from the pump 300 in the usual manner,but could enter it from the cooling circuit 317 through the conductor314, the valve 313 and the flow line 312 (since the low pressure in theconduit 311 would move the valve 313 to the position shown in FIGURE12); but fluid also could enter the conduit 311 from the circuit 317through the conduits 328 and 330. These are important features of thehydraulic control system and provide for safety and efliciency ofoperation of the apparatus at all times.

In FIGURE 14 is illustrated a modified form of hydraulic system forcontrolling the operation of the snubber slip assemblies and the blowoutpreventers. The source of fluid for the system may be the same reservoir320 as employed in the system illustrated in FIGURES 12 and 13 forcontrolling the snubbing piston, or may be a separate source. A constantvolume pump 450 delivers fluid from the reservoir 320 through a supplyconduit 451 to the manually operated four-way control valves 460, 461,and 462 which may be separately operated to control the operation of theslip assembly of the traveling snubber 40 and the slip assemblies 25 and24, respectively, of the stationary snubber. Check valves 452 and 453 inthe supply conduit prevent the reverse flow of fluid therein.

An accumulator 454 stores a volume of fluid under pressure, which itreceives from the supply line 451 through the conduit 456 and valve 457,and fluid from the accumulator is adapted to operate the slip assembliesand blowout preventers should the pump fail or a conduit break occur.

A spring loaded pressure reducer 470, set to operate to open at apressure of approximately 300 lbs. per square in., is inserted in theline 451 to produce a lower downstream pressure for operating theblowout preventers 18, 19, and 21. The reduced pressure isdelivered fromthe reducer through the line 471 to the manually operated four-wayvalves 472 to 476, respectively, for controlling operation of theblowout preventers and gate valves. The valves 472, 473, and 474, forexample, may be used to control the blowout preventers 18, 19, and 21,respectively, and the valves 475 and 476 may constitute the controls forgate valves, such as the valve 16.

A safety relief valve 480 is connected with the conduit 451 by a conduit481 and with the reservoir 320 by a conduit 482 and permits bypassinghydraulic fluid from the conduit 451 back to the reservoir in the eventof overloading of the system, and may operate to open, for example atpressures exceeding 1000 lbs. per sq. in.

An unloading valve 485, of the same type as the unloading valves 305 and345 of FIGURES 12 and 13, communicates with the supply conduit 451through a branch conduit 485a and with the reservoir 320 throughconduits 486 and 482. A pilot conduit 487 connected into the supplyconduit 451 beyond the check valve 452 transmits pressure from thatportion of the conduit 451 beyond the check valve 453 back to theunloading valve 485. This unloading valve may be set to operate at apressure in the range of from 300 to 600 lbs. per sq. in. When thepressure in the accumulator 454, and in the conduit 451 beyond the checkvalve 453, equals or exceeds that for which the valve 485 has been set,the valve is in its fully open position and will permit unrestrictedbypassing of the fluid therethrough and back to the reservoir, thuspermitting the pump 450 to operate constantly by circulating thepressure fluid through the circuit formed by the supply conduit 451, thebranch conduit 485a, the valve 485, the conduits 486 and 482, and a heatexchanger 491 and filter 492 to the reservoir. When the valves 460, 461and 462 are actuated to operate their respective slip assembly 40, 25 or24, the pressure in the supply conduit 451 may fall below the value forwhich the valve 485 has been set, whereupon said valve automaticallycloses, causing fluid pressure from the pump 450 to pass through thecheck valves 452 and 453 to the valves controlling actuation of the slipassemblies until the demand for fluid pressure is satisfied and untilthe circuit, including the accumulator 454, is re- 14 charged withsufiicient pressure to again shift the valve 485 to its fully openposition, which then permits unrestricted bypassing a-nd circulating ofthe hydraulic fluid from the pump through the valve back to thereservoir. Since the valve 485 holds no back pressure, no heat iscreated and needless overheating of the fluid and wastage of horsepowerare prevented.

The conduit 490 constitutes an exhaust line for ex hausting fluid fromthe cylinders for operating the slip assemblies, blowout preventers andgate valves which connect therewith.

The heat exchanger 491 and a filter 492 may be the same as or similar tothose employed in the circulating circuit 317 in FIGURE 12.

As a matter of convenience, all of the valves for controlling theoperation of the piston, the slip assemblies and the blowout preventersin addition to any other valve controls provided may be mounted on apanel installed at a suitable height above the platform 51 so that anoperator on the platform may have control of the entire apparatus at hisfingertips.

The structure of the slip assemblies employed in the present apparatusis illustrated in detail in FIGURE 8 which shows the two gripping slipassemblies 24 and 25 comprising the lower stationary snubber 26 shown inFIG- URE 1. As shown, the two gripping slip assemblies are mounted inopposed functional relationship so that one assembly can hold the tubingagainst longitudinal movement in one direction while the other assemblycan prevent movement of the tubing in the other direction. While all theslip assemblies incorporated in the apparatus are identical, it is to benoted that they are never all mounted for gripping action in the samedirection.

Each slip assembly 24, 25 and 40 includes a bowl or body 205 having atapered longitudinal bore 206 extending therethrough, and provided onits opposite ends with external annular hubs 205a by means of which thebodies of the slip assemblies may be connected together or to otherparts of the assembly. The two slip assemblies 24 and 25, comprising thestationary snubber 26, are fastened together by a split clamp ring 201secured by bolts 202 having nuts 203 thereon, said clamp ring engagingover the abutting annular hubs 205a of the two slip assemblies. The slipassembly of the travelling snubber 40 may also be connected to the upperend of the tubular piston rod 32 by an identical clamp ring securing theexternal annular hub of such assembly to an identical hub on the upperend of the tubular piston rod. Vertical dovetail slots 207 are formed inthe internal wall of the body of each of the slip assemblies to receivedovetail keys 208 on which slips 209 are slidably mounted. The slips ineach assembly are shown as four in number and, when viewed as a set, aresubstantially frusto-conical in shape. The outer surfaces of the slipsare tapered to conform substantially to the tapered bore 206 of theassembly body and each is provided with a vertical dovetail slot 210slidable on one of the dovetail keys. Each key is retained in itsassociated slip body by a lock screw 208a which extends through anaperture in the assembly body into the divergent ends of the slots 207.The slips 209 are slidable longitudinally in the tapered vertical bore206 of the body and are retained therein by the keys 208 cooperatingwith the dovetail grooves 210 in the outer surface of each slip. Thus,when the slips are moved toward the small end of the tapered body bore,the slips are cammed inwardly, and when moved in the opposite directiontoward the wide end of the bore, they are moved outwardly.

As will be seen in FIGURE 10, the curvature of the outer surfaces of theslips, however, is slightly greater than the curvature of the boresurface of the bowl or body 205, so that the conformity of the twosurfaces is not exact. This permits the slips to be slidably supportedby the keys 208 engaging in the slots 210 in the outer surfaces of theslips rather than engage the bore surface of the body throughout theirmovement longitudinally in the body, thus reducing friction and avoidingany binding of the lateral edges of the slips with the bore wall as theslips move into the smaller end of the bore of the body.

Each slip 209 is provided with an internal horizontal arcuate dovetailedslot 212 adapted to receive a slip insert 213 having an external arcuatedovetailed rib 213a thereon. Gripping teeth 214 are formed on thesubstantially cylindrical inner surface of the slips for engaging thewell tubing when the same is inserted through the slip assemblies. Theinserts are locked in place in the slips by set screws 214a threadedinto a threaded hole drilled and tapped in both the slip and the inserttherein.

The movement of the slips toward their outer or retracted positions islimited by their contact with the annular shoulder 215 of the internalflange 216 of the body. In the other direction, movement of the slips islimited by engagement with the tubing or, when no tubing is present inthe bore of the body, the inward movement of the slips toward operativetubing engaging or gripping position is limited by the mechanism whichactuates the slips or by the engagement of the slips with each other.

It is apparent that when the slips are moved to their outer retractedpositions, they will permit passage of the tubing through the bore ofthe body, and that when they are moved inwardly into gripping engagementwith the tubing, they will prevent such passage. It should also beunderstood that the slips will hold much better against movement of thetubing in one direction than the other. As the tubing is biased in onedirection either by well pressure or by gravity, the slip assembly ispositioned with the taper of the bore of the bowl and of the slipspointing in the direction of the tubing bias. Thus, the engagement ofthe tubing with the slips tends to wedge the slips inwardly as they movealong the tapered bore of the body to cause even firmer grippingengagement with the tubing, so that the greater the force on the tubingtending to move the tubing, the tighter will be the grip of the slipsthereon.

The slips also provide a holding action against tubing movement in theother direction but to a much lesser degree, and the slip assemblies arepreferably not used to grip and hold the pipe against movement undersuch conditions. Instead, the slip assemblies are so disposed that thetaper of the bore of the bowl or body and the taper of the slips wedgethe slips into tighter gripping engagement with the tubing when thetubing is moved longitudinally by such biasing force acting thereon.

The body 205 is provided with bosses 220 on opposite sides thereof, eachhaving a window 221 opening from the exterior of the body to the bore206. A horizontal shaft 222 is mounted in a transverse bore in each ofthe bosses and extends transversely across the window therein, and eachshaft carries a slip pivot arm 223 which extends inwardly through thewindow into the bore of the body for moving the pair of slips 209disposed therein adjacent such window. Keys 224 prevent rotation of thepivot arm relative to the shaft. An operating lever 225 is installedexternally of the body and connected to one end of each shaft, the shaftbeing provided with a reduced end portion which extends through anaccommodating aperture in one end of the lever. Each lever is retainedon its shaft 222 by an end plate 226 and an axial screw 227, while keys228 assure that the shaft will be rotated by the operating lever as thesame is moved, the slip pivot arm being moved thereby to move the slips,as will be explained. A pair of bearings 229 and 230 are mounted in thebores of each of the bosses 220 on either side of the pivot armto reducerotational friction between the shaft and bosses and facilitate movementof the slip pivot arms by swinging movement of the operating levers.Washers 231 reduce the friction between the body and the head 222a ofthe shaft, and a bearing shim 232 spaces the shaft end of each operatinglever from the body 205.- The other end of each operating lever 225 isproever port is the fluid inlet port.

vided with a slot 234, and a synchronizing pin 235 extends through saidslots and has an inner base end 238 slidably mounted in a verticaldovetail slot 236 formed in the external wall of the body. As shown inFIGURES 8 and 9 the base slides in the slot 236 and acts as a guide andto assure smooth vertical reciprocable movement of the pin. Since thepin extends through the slots 234 in both of the operating levers 225,the levers are linked to move in synchronism when the pin is caused tomove up or down.

An up or down movement is imparted to the pin by means of a verticalpiston rod 237 which has a bearing member 238a at its upper end engagedaround the outer end of pin 235 whereby vertical movement of the pistonmoves the pin therewith, and since the pin is engaged in the slots 234in the operating levers 225, also causes the slip pivot arms to swingabout the axes of the shafts 222. The inner free end of each of thepivot arms has a crosspin portion 22342. which engages in slots 209aformed in the outer portion of the laterally thicker ends of each of theslip 209. As the slips are moved up and down in the tapered bore 206 onthe dovetailed keys 208, they also move toward and away from one anotherand the vertical space between them varies considerably. Accordingly,each pivot arm 223 is reduced in thickness near its inner end, as at2231), so that this portion will not be engaged by or prevent movementof the slips when they are moved. Each of the slips is also relievedadjacent the slots 209a, as at 2199b (see FIGURES 8 and 10), to provideroom for the reduced portion 223b of the pivot arm when the slips arewedged inwardly toward their tubing engaging position by movement towardthe reduced portion of the bore of the body.

The piston rod 237 of the lower slip assembly 24 of FIGURE 8 extendsdownwardly through a gland 240 mounted in the upper end of a hydrauliccylinder 244 secured by bolts 244a to the side of the body below theoperating levers. A piston 241, slidably mounted in the bore 243 of thecylinder 244 is connected to the lower end of the piston rod, and thecylinder extends parallel with the longitudinal axis of the body inalignment with the piston rod. The piston is locked on the piston rod bya lock nut 245. A piston seal ring 242, disposed in an external annulargroove in the piston, seals between the piston and the wall of the bore243. Hydraulic operating fluid is conducted into and out of the bore ofthe cylinder above the piston through a lateral port 247 which isconnected by means of a suitable conduit 247a with a valve in ahydraulic system, such as the system disclosed in FIG- URE 6, while alateral port 248 at the lower end of the cylinder provides means forconducting hydraulic fluid by means of a conduit 248a into and out ofthe bore of the cylinder below the piston. Introduction of fluidpressure into the cylinder through one of the ports at the same timefluid is conducted out of the cylinder through the other port to thereservoir of the hydraulic system will cause the piston to slidably movewithin the cylinder. The direction of movement of the piston, of course,is away from which- It is thus apparent that the slip gripping inserts213 can be engaged wit-h or disengaged from the tubing at will asdetermined by the introduction of fluid pressure to the chambers oneither side of the piston.

It will also be seen that movement of the slips toward tubing engagnigposition is, in the absence of tubing, limited by the engagement of theexternal shoulder 238b of the bearing member 238a. on the piston rodwit-h the adjacent end of the cylinder 244 and the packing gland 240.Should it be desired to positively lock the slips in gripping engagementwith the tubing, a lock screw 250 is threaded into an opening 251 in theexterior of the body 205, and a cap screw 252 is threaded through anaccommodating eye or aperture in the lock screw and tightened againsteach operating lever 225, as shown in the upper slip assembly of FIGURE8, to prevent swinging pivotal movement of such operating lever. By thismeans, the slip pivot arms are likewise held against swinging movementand, therefore, hold the several slips locked in their tubing engagingposition for any desired period of time without the necessity ofmaintaining fluid pressure in the cylinder 244.

At the connection of the two slip assemblies 24 and 25, forming thelower stationary snubber 26, an annular tu bing guide 255 is held inguiding centralizing position in the bore of the two assemblies, asshown in FIGURE 8. The guide includes an external peripheral flange 256which is positioned in a groove formed between the shoulders 256a in theinternal bore walls of the assembly bodies 205. Similar guides may beplaced at longitudinally spaced distances in the bore of the apparatusto serve to hold the tubing in alignment with the axis of the apparatusso that the slips and the seal members of the blowout preventers willengage the tubing without difiiculty. In addition, the guides serve toprevent the tubing from buckling or bending, thus enabling it towithstand the greater column loads encountered when working with highwell pressures.

It will be apparent that the snubbing apparatus, described herein, isreadily adaptable to handle tubing of various diameters by replacing thesealing ram inserts of the blowout preventers, the slip inserts 213, andthe guides 255, with corresponding elements of a size to accommodate thesize of tubing to be handled.

It will also be seen that the coaxial arrangement and longitudinalmovement of the tubular piston rod and annular piston, through which thelength of tubing or pipe to be moved thereby is inserted, and the factthat such tubing or pipe is disposed axially in and gripped by thegripping means carried by the tubular piston rod, provides for theapplication of a laterally balanced longitudinal force to the tubing orpipe thereby substantially eliminating buckling or bending of the tubingor pipe as the same is forced into the well against pressure.

It will be further be seen from the foregoing description that a fluidpressure operated apparatus for running or pulling a well conductor ortubing under pressure has been provided, and that the apparatus issupportable on the wellhead itself rather than on an elaborate structurefooted on the earths surface, whereby it is particularly adapted for useon offshore or marine wells having no platforms or derricks or othersupporting structures. In addition, it will be noted that the controlmechanisms for the snubbing device disclosed herein and the personnelfor operating the same are also entirely supported .by the wellhead.

From the foregoing, it will readily be apparent that the several membersconnected above the wellhead, including the gate valve, blowoutpreventers, the stationary snubber, the operator means and the travelingsnubber all comprise a body or housing having a longitudinal passagetherethrough through which the well pipe or rods or the like are moved,and that the entire housing including the valves, blowout preventers,snubbers and operator means for the snubbers are mounted solely on thewellhead, whereby the wellhead provides a support for all operationsconducted in the well by use of such apparatus.

It will further be seen that the lower stationary snubber 26 includingthe two gripping assemblies 24 and 25, together with the upper travelingsnubber 40 and the hydraulic fluid actuated operator means for eflectinglongitudinal movement of the traveling snubber toward and away from thestationary snubber constitutes a hydraulically operated snubbingapparatus, and that an improved hydraulic system has been provided forautomatically hydraulically locking the snubbing apparatus againstlongitudinal movement in the event of failure of hydraulic fluidpressure in the system.

It will also be readily apparent that the plurality of blowoutpreventers comprise a plurality of seal means carried by the housing formoving into and out of sealing engagement with the pipe or rodsextending through the housing to effect movement thereof of such pipe orrods through the housing into the Well by providing means for passingexternally enlarged couplings and the like through the sealing elementsof the rams of the blowout preventers.

It will also be seen that the slip assembly disclosed herein, whileactuatable in response to application of fluid pressure, may be lockedmechanically and held in operative position independently of the fluidpressure.

The foregoing description of the invention is explanatory only, andchanges in the details of the construction illustrated and the systemdescribed may be made by those skilled in the art, within the scope ofthe appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A snubbing assembly adapted to be mounted solely on a wellhead forcontrolling the movement of tubing under pressure in a well comprising:a seal assembly mounted on said wellhead having a bore extendingtherethrough and adapted to sealingly engage a length of tubingextending through said bore to confine the well pressure of said well;and means for applying a laterally balanced longitudinal force to saidtubing for holding and running said tubing into or out of said well,said means including; first tubing gripping means having a boreextending therethrough and supported on said seal assembly, saidgripping means being adapted to grip said length of tubing receivedwithin its axial bore to hold and support the same against longitudinalmovement therein; means providing an annular chamber and having an axialbore and supported on said first gripping means; a tubular piston memberhaving an axial bore and disposed within said annular chamber andco-axial therewith, said tubular piston member being mounted in saidannular chamber for relative axial longitudinal movement thereof; secondtubing gripping means having a bore extending therethrough and mountedon said tubular piston member at an end thereof which is remote fromsaid first gripping means, said second gripping means being adapted togrip said length of tubing inserted in said tubular piston; member meansconnecting said second gripping means with said piston member formovement of said second gripping means by said piston memberlongitudinally relative to said chamber, all of said bores being alignedwith the bore of said well to define a passage for passage of saidlength of well tubing therethrough; said first gripping means beingengaged with said tubing to hold and support the same againstlongitudinal movement while said second gripping means is disengagedfrom said tubing, and said second gripping means being engaged with saidtubing for gripping and moving the same longitudinally when said firstripping means is disengaged from said tubing, whereby said tubing may bemoved lougitudinally of said bores or said passage; and fluid pressuremeans for imparting laterally balanced longitudinal movement to saidtubular piston member in alternating reciprocal directions whereby saidlength of tubing received within the bore of said tubular piston memberand gripped by said second gripping means may be moved thereby throughsaid passage into or out of the well as determined by the direction ofmovement imparted to said tubular piston member.

2. A snubbing assembly adapted to be mounted solely on a wellhead forcontrolling the movement of tubing under pressure in a well comprising:a seal assembly mounted on said wellhead having a bore extendingtherethrough and adapted to sealingly engage a length of tubingextending through said bore to confine the well pressure of said well;first tubing gripping means having a bore extending therethrough andconnected to and supported on said seal assembly, said gripping meansbeing adapted to grip said length of tubing received within its bore tohold the same against longitudinal movement therein; means providing anelongate annular chamber having an axial bore extending therethrough andconnected to and supported on said first gripping means; a tubularpiston member having an axial bore and disposed within said annularchamber in co-axial relation therewith, said tubular piston member beingmounted within said annular chamber for relative longitudinal axialmovement thereof; second tubing gripping means having a bore extendingtherethrough; an elongate tubular memher having one end connected tosaid piston member in said chamber and the opposite end thereofconnected to said second tubing gripping means, said second grippingmeans being mounted on said tubular member at an end thereof which isremote from said wellhead, said second gripping means being adapted togrip said length of tubing inserted in said tubular member, all of saidbores being aligned with the bore of said well to define a passage forsaid length of well tubing; said first gripping means being engaged withsaid tubing to hold and support the same against longitudinal movementwhile said second gripping means is disengaged therefrom, and saidsecond gripping means being engaged with said tubing for grip ping andmoving the same longtudinally when said first gripping means isdisengaged therefrom, whereby said tubing may be moved longitudinally ofsaid passage; and means for imparting axial movement to said tubularpiston member in alternating reciprocal directions whereby said lengthof tubing received within the bore of said means forming said annularchamber and the bore of said tubular member and gripped by said secondgripping means may be moved through said passage into or out of saidwell as determined by the direction of movement imparted to said tubularpiston member.

3. A gripping assembly comprising: a body having a bore extendingtherethrough: a plurality of gripping means movable on said body betweena retracted position and an inward operative position wherein saidgripping means are engageable with an elongate member received in saidbore to grip said elongate member; means on said body responsive tofluid pressure to alternately move said gripping means between saidretracted and said operative positions; and locking means on said bodyengageable with said means for moving said gripping means betweenretracted and operative positions for locking said gripping means insaid operative position.

4. A gripping assembly for gripping elongate objects comprising: a bodyhaving a bore extending therethrough;

a plurality of gripping means movable on said body between a retractedposition and an inward operative position wherein said gripping meansare engageable with an elongate object received in said bore to gripsaid elongate object; means on said body responsive to fluid pressure toalternately move said gripping means between said retracted and saidoperative positions; locking means on said body engageable with saidmeans for moving said gripping means between retracted and operativepositions for locking said gripping means in said operative position;and means on said body and said locking means coengageable for movingsaid locking means into engagement with said means for moving saidgripping means to lock said gripping means in gripping positionindependently of the maintenance of said fluid pressure.

5. A gripping assembly comprising: a body having a bore having meanstherein providing a plurality of tapered camming surfaces; a pluralityof gripping means slidably supported on the camming surfaces in saidbore for movement between an outer retracted position and an inneroperative position wherein said gripping means are adapted to engage andgrip an elongate object in said bore; means on said body responsive tofluid pressure to alternately move said gripping means along saidcamming surfaces between said retracted and operative positions; andlock means on said body movable into engagement with said means formoving said gripping means between retracted and operative positionsindependent of fluid pressure for moving said gripping means betweenretracted" and operative positions to lock said gripping means in saidoperative position.

6. A gripping assembly for gripping a length of tubing comprising: abody having a bore extending therethrough; the wall of said bore beingprovided with a plurality of circumferentially spaced longitudinallyextending camming surfaces; a plurality of circumferentially spacedgripping means each slidably movable on one of said camming surfacesbetween an outer retracted position and an inner operative positionwherein said gripping means is adapted to engage and grip a length oftubing inserted in said bore, said camming surfaces and complementarygripping means being disposed in circumferentially spaced pairs; meansoperatively connecting adjacent pairs of said gripping means formovement in pairs along said camming surfaces; means on said bodyactuable by application of fluid pressure operatively connected withsaid connecting means for movement of said connecting means to move saidpairs of gripping means along said camming surfaces between saidretracted and said operative positions.

7. A gripping assembly for gripping a length of well tubing comprising:a support member having a bore communica-ting at both ends with theexterior of said support member; a plurality of tapered longitudinallyextending circumferentially spaced camming members in said supportmember bore; a plurality of circumferentially spaced gripping meansmovably mounted in said support member and each supported in cammingengagement with 21 separate one of the camming members in said bore;said gripping means being movable within said bore between an outerretracted position and an inner operative position wherein said grippingmeans are adapted to engage a length of well tubing inserted in saidbore, said gripping means and complementary camming members beingdisposed in circumferentially spaced pairs; connecting means operativelyconnecting adjacent pairs of said gripping means for movement of each ofsaid pairs of gripping means as a unit on said camming members; means onsaid support member operatively associated with said connecting meansand responsive to fluid pressure for alternately moving said connectingmeans to move the pairs of gripping means operatively connectedtherewith between said retracted and operative positions.

8. A gripping assembly for gripping a length of well tubing comprising:a support member having a tapered bore communicating at both ends withthe exterior of said support member; a plurality of circumferentiallyspaced longitudinally extending supporting keys in said bore disposed inan inwardly and downwardly converging position with respect to eachother; gripping means movably mounted on said supporting keys andslidable longitudinally thereon on said keys within said tapered borebetween an outer retracted position and an inner operative grippingposition wherein said gripping means is adapted to engage a length ofwell tubing inserted in said bore; means on said support memberresponsive to fluid pressure for alternately moving said gripping meansbetween said retracted and operative positions; and lock means on saidsupport member engageable with said means for moving said gripping meansbetween retracted and operative positions for locking said grippingmeans in said operative position.

9. An apparatus for moving pipe or rods comprising: a pair of co-axialcylinders defining an annular chamber therebetween, the inner one ofsaid cylinders having a bore extending therethrough; first fixedgripping means secured to the outer cylinder and having means thereonproviding for connection thereof to a well flow conductor and operablefor gripping a pipe or rod extending through said inner cylinder; meansformoving said first gripping means into and out of position forgripping said pipe or rod to prevent longitudinal movement thereof; anannular piston slidably mounted in said annular chamber for longitudinalmovement relative to said cylinders; means for applying fluid pressureagainst a selected side of said piston to impart movement thereto withinsaid annular chamber; second gripping means connected with said pistonand operable for gripping a pipe or rod disposed within said innercylinder bore; fluid pressure operated means for moving said secondgripping means into and out of position for gripping said pipe or rod;elongate piston rod means connecting said second gripping means and saidpiston whereby said second gripping means is connected to said piston tomove therewith toward and away from said first gripping means wherebysaid length of pipe or rod disposed in said bore may be movedtherethrough in a direction determined by the direction of movementimparted to said piston.

10. An apparatus of the character set forth in claim 9 wherein saidpiston rod means comprises an elongate annular sleeve disposed axiallyin and movable longitudinally of said annular chamber connecting saidannular piston with said gripping means, means on said cylinders andsaid sleeve coengageable during longitudinal movement of sleeve, wherebysuch axial mounting of said sleeve in said chamber provides forapplication of a laterally balanced longitudinal force to said grippingmeans longitudinally of the bore of said inner cylinder.

11. An apparatus for moving pipe or rods comprising: a pair of co-axialcylinders defining an annular chamber therebetween, the inner one ofsaid cylinders having a bore extending therethrough, an annular pistonslidably mounted in said annular chamber for longitudinal movementrelative to said cylinders; means for applying fluid pressure against aselected side of said piston to impart movement thereto within saidannular chamber; first fixed gripping means secured to the outer of saidcylinders and having means thereon providing for connection thereof to awell flow conductor and operable for gripping a pipe or rod extendingthrough said inner cylinder; means for moving said first gripping meansinto and out of position for gripping said pipe or rod to preventlongitudinal movement thereof; second gripping means alternatelyoperable for gripping and releasing a pipe or rod disposed within saidinner cylinder bore; fluid pressure operated means for moving saidsecond gripping means between gripping and releasing positions; meansconnecting said second gripping means to said piston to move therewithwhereby said length of pipe or rod disposed in said bore may be movedtherethrough in a direction determined by the direction of movementimparted to said piston; and means acting on said piston to positivelyhold the same against movement in said annular chamber to preventundesired longitudinal movement of said second gripping means connectedwith said piston relative to said chamber.

12. An apparatus for moving pipe or rods comprising: a pair of co-axialcylinders defining an annular chamber therebetween, the inner one ofsaid cylinders having a bore extending therethrough; an annular pistonslidably mounted in said annular chamber for longitudinal movementrelative to said cylinders; means for applying fluid pressure against aselected side of said piston to impart movement thereto within saidannular chamber; first fixed gripping means secured to the outer of saidcylinders and having means thereon providing for connection thereof to awell flow conductor and operable for gripping a pipe or rod extendingthrough said inner cylinder; means for moving said first gripping meansinto and out of position for gripping said pipe or rod to preventlongitudinal movement thereof; second gripping means alternatelyoperable for gripping and releasing a pipe or rod disposed within saidinner cylinder bore; fluid pressure operated means for moving saidsecond gripping means between gripping and releasing positions; meansconnecting said second gripping means to said piston to move therewithwhereby said length of pipe or rod disposed in said bore may be movedtherethrough in a direction determined by the direction of movementimparted to said piston; and fluid pressure control means controllingthe fluid pressure acting on said piston to positively hold said pistonagainst longitudinal movement in said chamber to prevent undesirablelongitudinal movement of said second gripping means connected with saidpiston relative to said chamber.

13. An apparatus for moving pipe or rods comprising: a pair of co-axialcylinders defining an annular chamber therebetween, the inner one ofsaid cylinders having a bore extending therethrough; first fixedgripping means secured to one end of the outer of said cylinders andhaving means adapted for connecting the same to a well flow conductorand operable to grip a pipe or rod disposed within the bore of the innercylinder to prevent longitudinal movement of said pipe or rod; means foroperating said first gripping means into and out of gripping position;an annular piston slidably mounted in said annular chamber forlongitudinal movement relative to said cylinders; means for applyingfluid pressure against a selected side of said piston to impart movementthereto within said annular chamber; second gripping means for grippinga pipe or rod disposed within said inner cylinder bore; means connectingsaid second gripping means with said piston to move said second grippingmeans longitudinally with said piston toward and away from said fixedgripping means; and means for actuating said second gripping means intoand out of gripping engagement with said pipe or rod whereby said pipeor rod disposed in said bore may be moved therethrough in a directiondetermined by the direction of movement imparted to said piston.

14. An apparatus for moving elongate objects com prising: a pair ofco-axial cylinders defining an annular chamber therebetween, the innerone of said cylinders having a bore extending therethrough; an annularpiston slidably mounted in said annular chamber for longitudinalmovement relative to said cylinders; means communicating with saidannular chamber for introducing fluid pressure therein at opposite sidesof said piston; control means for varying the fluid pressure on oppositesides of the piston to move said piston in a selected longitudinaldirection of said cylinder; first fixed gripping means secured to oneend of the outer one of said cylinder and having means thereon adaptedfor connection with a well flow conductor and operable to grip anelongate object disposed within the bore of said inner cylinder toprevent longitudinal movement of said elongate object; fluid pressuremeans for actuating said first gripping means into and out of positionfor gripping said elongate object to hold the same against movementrelative to said outer cylinder and said chamber; second gripping meansselectively operable for gripping an elongate object disposed withinsaid inner cylinder bore; means for actuating said second gripping meansinto and out of position for gripping said elongate object; and meansconnecting said second gripping means to said piston to move therewithlongitudinally toward and away from said first fixed gripping meanswhereby said elongate object disposed in said bore may be movedtherethrough in a direction determined by the direction of movementimparted to said piston.

15. A snubbing apparatus for moving pipe or rods into and out of a wellincluding: a stationary snubber; a traveling snubber; hydraulic fluidpressure actuated operator means connecting said stationary snubber andsaid traveling snubber and actuatable to move said traveling snubbertoward and away from said stationary snubber, said operator meansincluding a cylinder and a piston movable therein by hydraulic fluidpressure; and a hydraulic system for controlling reciprocal movements ofsaid piston longitudinally in said cylinder comprising a source of fluidpressure; means for selectively communicating said pressure to eitherside of the piston Within said cylinder; a first valve means operable toexhaust the fluid in said cylinder on one side of said piston; a secondvalve means operable to exhaust the fluid in said cylinder on the otherside of said piston; and means for communicating fluid pressure fromsaid source to the one of said valve means which controls the exhaust offluid from said cylinder on the side of the piston opposite that towhich fluid pressure is selectively applied, each of said valve meansbeing operable in response to predetermined fluid pressure communicatedthereto from said source, whereby such predetermined fluid pressure isrequired to open said one valve means to permit exhausting of fluidsfrom the cylinder and whereby said one valve means closes when saidpressure falls below said predetermined pressure to prevent furthermovement of said piston within said cylinder.

16. An apparatus for moving pipe or rods into and out of a well underpressure, said well being provided with a wellhead and having a pipe orrod extending therethrough into said well, said apparatus including: ahousing defining an elongate passage; means at the lower end of thehousing for connecting and supporting said housing solely on saidwellhead with said passage in alignment with the bore of the well; aplurality of seal means spaced longitudinally of and carried by saidhousing and movable into and out of sealing engagement with said pipe orrod when the same is disposed in said passage to prevent fluid flow fromthe well through said passage externally of said pipe or rod past saidseal means; and means for applying a laterally balanced longitudinalforce to said pipe or rod for holding and moving said pipe or rod intoand out of said well, said means incuding: a first gripping meanscarried by said housing for gripping said pipe or rod when disposed insaid passage to hold and support the same against longitudinal movement;a pair of coaxial cylinders defining an annular chamber therebetween andforming a part of said housing and having a bore in axial alignment withthe bore of the well; an annular piston slidably mounted in said annularchamber for longitudinal movement relative to said cylinders; means forapplying fluid pressure against a selected side of said piston to efiectmovement thereof with respect to said annular chamber; an annular pistonrod connected with said annular piston and extending upwardly therefromout of said annular chamber; a second gripping means for gripping pipeor rod disposed in said passage carried on the projecting end of saidpiston rod and movable therewith, whereby movement of the piston and thepiston rod connected therewith causes longitudinal movement of saidsecond gripping means relative to said first gripping means; said firstgripping means being engaged with said pipe or rod to hold and supportthe same against longitudinal movement while said second gripping meansis disengaged from said tubing, and said second gripping means beingengaged with said tubing for gripping and moving the same longitudinallywhen said first gripping means is disengaged from said tubing, wherebysaid tubing may be moved longitudinally of said passage; and hydrauliccontrol means for controlling the introduction of hydrauic fluidpressure into said annular chamber to efiect movement of said piston andthe second gripping means connected therewith, the axial mount ing ofthe tubular piston rod in the annular cylinder having the boretherethrough receiving the pipe or rod and applying a longitudinallaterally balanced force through said second gripping means to said pipeor rod to move the same into the well bore.

17. A snubbing apparatus for moving elongate objects longitudinally witha longitudinal laterally balanced force and comprising: a pair ofcoaxial cylinders defining an annular chamber therebetween, the innerone of said cylinders having a bore extending therethrough for receivingthe elongate object to be moved; an annular piston slidably mounted insaid annular chamber for longitudinal movement relative to saidcylinders; a tubular connecting rod connected at one end with saidannular piston and extending therefrom beyond the end of the annularchamber defined by the coaxial cylinders; gripping means carried by saidprojecting end of said tubular piston rod,

-said gripping means being hydraulically operated for gripping anelongate object disposed within said inner cylinder bore and within saidtubular piston rod; conduit means connected with said annular chamber onopposite sides of said piston for introducing hydraulic fluid pressureinto said chamber for etfecting longitudinal movement of the piston insaid chamber whereby the gripping means is moved longitudinally withsaid piston by means of the piston rod connecting the two; control meansin said conduit means for varying the fluid pressure on opposite sidesof the piston to move said piston in a selected longitudinal directionin said cylinders; and a second gripping means on the opposite end ofsaid cylinders and connected therewith for gripping said elongate objectto hold the same against movement while the movable first gripping meansis being moved to position for re-engagement with said elongate object.

18. A snubbing apparatus of the character described in claim 17 whereinthe control means for varying the fluid pressure on opposite sides ofthe piston to move said piston comprises a source of fluid pressure, avalve means connected in said conduit means operable to exhaust thefluid in said cylinder and said chamber on one side of said piston; afirst valve means and second valve means in said conduit means operableto direct fluid pressure from said source into said chamber on saidopposite side of said piston to cause movement of said piston in saidchamber, said first valve means being operable in response to apredetermined fluid pressure communicated thereto from said source topermit fluid to be expelled from said chamber and to close when saidfluid pressure applied to said first valve means falls below saidpredetermined value, whereby movement of the piston is stopped.

19. A snubbing apparatus for moving pipe or rods into and out of a wellincluding: a stationary snubber; a traveling snubber; hydraulic fluidpressure actuated operator means connecting said stationary snubber andsaid traveling snubber and actuatable to move said traveling snubbertoward and away from said stationary snubber, said operator meansincluding an annular cylinder and a piston movable therein by hydraulicfluid pressure and having means connecting it with said travellingsnubber whereby said traveling snubber is movable with said piston; anda hydraulic system for controlling reciprocal movements of said pistonlongitudinally in said cylinder comprising: a source of fluid pressure;conduit means communicating said pressure from said source to each sideof the piston within said cylinder; a first valve means in said conduitmeans operable to exhaust the fluid in said cylinder on one side of saidpiston; a second valve means in said conduit means operable to exhaustthe fluid in said cylinder on the other side of said piston; means forcommunicating fluid pressure from said source to the one of said valvemeans which controls the exhaust of fluid from said cylinder on the sideof the piston opposite that to which fluid pressure is selectivelyapplied, said valve means being operable in response to predeterminedfluid pressure communicated thereto from said source, whereby suchpredetermined fluid pressure is required to open said one valve means topermit exhausting of fluids from the cylinder and whereby said one valvemeans closes when said pressure falls below said predetermined pressureto prevent further movement of said piston within said cylinder; andseal means between said operator means and said well pipe or rods.

20. An apparatus for moving under pressure pipe or rods into and out ofa well provided with a wellhead and having a pipe or rod extendingthereinto, said apparatus including: a housing defining an elongatepassage; means at the lower end of the housing for connecting andsupporting said housing solely on a wellhead with said passage incommunication with the bore of the well; a plurality of longitudinallyspaced seal means carried by said housing for moving into and out ofsealing engagement with said pipe or rod when disposed in said passageto prevent fluid flow from the well through said passage past said sealmeans externally of said pipe or rod; a first gripping means carried bysaid housing above said plurality of seal means for gripping said pipeor rod disposed in said passage to hold the same against longitudinalmovement therein; a second gripping means for gripping said pipe or roddisposed in said passage, said second gripping means beinglongitudinally spaced above said first gripping means and movablelongitudinally of said housing relative thereto; means supported by saidhousing for supporting and moving said second gripping means relative tosaid first gripping means; said first gripping means being engaged withsaid pipe or rod to hold and support the same against longitudinalmovement while said second gripping means is disengaged from said pipeor rod, and said second gripping means being engaged with said pipe orrod for gripping and moving the same longitudinally of the housing whensaid first gripping means is disengaged from said pipe or rod, wherebysaid pipe or rod may be moved longitudinally of said housing by saidsecond gripping means; and means for actuating said means for movingsaid second gripping means, for actuating said seal means, and foractuating said gripping means, each independently of the other, wherebysaid seal means and said gripping means may be moved into and out ofengagement with said length of pipe or rod disposed in said passage andsaid means for moving said second gripping means may be operated to movesaid second gripping means so that said pipe or rod may be moved throughsaid passage under pressure into or out of said well.

21. An apparatus for moving under pressure pipe or rods into and out ofa well provided with a wellhead and having a pipe or rod extendingthereinto, said apparatus including: a housing defining an elongatepassage; means at the lower end of the housing for connecting andsupporting said housing on said wellhead with said passage incommunication with the bore of the well; a plurality of seal meansspaced longitudinally of and carried by said housing for moving into andout of sealing engagement with said pipe or rod when disposed in saidpassage to prevent fluid flow from the well through said passageexternally of said pipe or rod past said seal means; a first meanscarried by said housing for gripping said pipe or rod disposed in saidpassage for holding and supporting said pipe or rod against longitudinalmovement therein; a pair of coaxial cylinders defining an annularchamber therebetween and supported on said housing in axial alignmentwith the bore of said well; an annular piston slidably mounted in saidannular chamber for longitudinal movement relative to said cylinders;means for applying fluid pressure against a selected side of said pistonto impart movement thereto within said annular chamber; a secondgripping means for gripping said pipe or rod disposed in said passage;means connecting said second gripping means to said piston to movetherewith; said first gripping means being engaged with said pipe or rodto hold and support the same against longitudinal movement while saidsecond gripping means is disengaged from said pipe or rod, and saidsecond gripping means being engaged with said pipe or rod for grippingand moving the same longitudinally of the housing when said firstgripping means is disengaged therefrom, whereby said pipe or rod may bemoved longitudinally of said housing by said second gripping means;means for actuating said means for applying fluid pressure against saidpiston, for actuating said seal means, and for actuating said grippingmeans, each independently of the other, whereby said seal means and saidgripping means may be moved into and out of engagement with said lengthof pipe or rod disposed in said passage and said means for applyingfluid pressure against said piston to move the same may be actuated tomove said piston and the second gripping means carried thereby formoving the same longitudinally, whereby said pipe or rod may be movedthrough said passage and into or out of said well as determined by thedirection of movement imparted to said piston.

22. An apparatus of the character set forth in claim 21 wherein saidmeans for connecting said piston with said second gripping meanscomprises: an elongate tubular sleeve disposed axially in and movablelongitudinally of said annular chamber connecting said annular pistonwith said second gripping means, such axial mounting of said sleeve insaid chamber between said cylinders providing for application of alaterally balanced longitudinal force to said second gripping means.

23. In an apparatus of the character set forth in claim 21 for movingpipe or rods into and out of a well, a hydraulic system for controllingreciprocal movements of said piston slidably mounted in said annularchamber comprising: a source of fluid pressure; means communicating saidpressure to one side of the piston within said annular chamber; valvemeans operable to exhaust the fluid in said annular chamber on the otherside of said piston; and means for communicating fluid pressure fromsaid source to said valve means, said valve means being operabale inresponse to a predetermined level of fluid pressure communicated theretofrom said source.

24. In an apparatus of the character set forth in claim 21 for movingpipe or rods into and out of a Well, a hydraulic system for controllingreciprocal movements of said hydraulic pressure operated pipe engagingand moving means including said annular chamber and said piston slidablymounted in said annular chamber and comprising: a source of fluidpressure; means communicating said pressure to one side of the pistonwithin said annular chamber; a normally closed valve means operable toexhaust the fluid in said annular chamber on the other side of saidpiston to said source, and means for communicating fluid pressure fromsaid source to said valve means, whereby said valve means is opened inresponse to a predetermined fluid pressure communicated thereto fromsaid source to permit the flow of fluids from said annular chamber andwhereby said valve means is closed when said fluid pressure communicatedto said valve means falls below said predetermined pressure.

25. An apparatus for moving under pressure elongate objects into and outof a well provided with a wellhead and having an elongate objectextending therethrough into said well, said apparatus including: ahousing defining an elongate passage; means at the lower end of thehousing for connecting and supporting said housing solely on a wellheadwith said passage in alignment with the bore of the well; a plurality oflongitudinally spaced seal means carried by said housing for moving intoand out of sealing engagement with said elongate object disposed in saidpassage to prevent fluid flow from the well through said passage pastsaid seal means externally of said elongate object; a first grippingmeans carried by said housing above said plurality of seal means forgripping said elongate object disposed in said passage to hold saidobject against longitudinal movement in said passage; a second grippingmeans for gripping said elongate object disposed in said passage, saidsecond gripping means being longitudinally spaced from and above saidfirst gripping means and movable relative thereto longitudinally of saidhousing; means supported by said housing and connected with said secondgripping means for supporting and moving said second gripping meanslongitudinally relative to said first gripping means; said firstgripping means being engaged with said elongate object to hold andsupport the same against longitudinal movement while said secondgripping means is disengaged therefrom, and said second gripping meansbeing engaged with said elongate object for gripping and moving the samelongitudinally of the passage when said first gripping means isdisengaged therefrom, whereby said elongate object may be movedlongitudinally of said passage; and means for actuating said means formoving said second gripping means longitudinally, for actuating saidseal means and for actuating said gripping means, each independently ofthe other, whereby said seal means and said gripping means may be movedinto and out of engagement with said elongate object disposed in saidpassage and said means for moving said second gripping means may beoperated to move said second gripping means so that said elongate objectmay be moved longitudinally through said passage and into or out of saidwell.

26. A snubbing assembly adapted to be mounted solely on the wellhead forcontrolling the movement of tubing under pressure in a well comprising:a seal assembly mounted on said wellhead having a bore extendingtherethrough and adapted to sealingly engage a length of tubingextending through said bore to confine the pressure of said well; firsttubing gripping means having a bore extending therethrough and connectedto and supported on said seal assembly, said gripping means beingadapted to grip sai-d length of tubing inserted in the bore thereof tohold the same against longitudinal movement; a pair of co-axialcylinders defining an annular chamber therebetween and connected to andsupported on said first gripping means, the inner one of said cylindershaving a bore extending therethrough; an annular piston slidably mountedin said annular chamber for longitudinal movement relative to saidcylinders; a tubular piston rod secured to said piston and disposedabout said inner cylinder in co-axial relation therewith and extendingupwardly out of the upper end of said annular chamber; second tubinggripping means mounted on the projecting end of said tubular piston rodremote from said wellhead, said second gripping means being adapted togrip said length of tubing inserted in the bore of said inner cylinder,all of said bores being aligned with the bore of said well to form apassage for said length of tubing; said first gripping means beingengaged with said tubing to hold and support the same againstlongitudinal movement while said second gripping means is disengagedtherefrom, and said second gripping means being engaged with said tubingfor gripping and moving the same longitudinally of said passage whensaid first gripping means is disengaged therefrom, whereby said tubingmay be moved longitudinally of said passage by said sec ond grippingmeans; means communicating with said outer cylinder for applying fluidpressure against a selected side of said piston to impart movementthereto within said annular chamber to move said tubular piston rod andsaid second gripping means connected thereto, whereby said length oftubing inserted within the bore of said inner cylinder and gripped bysaid second gripping means may be moved through said passage in adirection determined by the direction of movement imparted to saidtubular piston rod.

27. In an apparatus of the type set forth in claim 26 for moving pipe orrods into and out of a well, a hydraulic system for controllingreciprocal movements of said piston slidably mounted in said annularchamber comprising: means for selectively communicating fluid pressureto either side of the piston within said annular chamber; a first valvemeans operable to exhaust fluid in said annular chamber on one side ofthe piston; a second valve means operable to exhaust fluid in saidchamber on the other side of said piston; bias means for biasing saidfirst and second valve means to normally closed position; and means forcommunicating fluid pressure to a selected one of said valve means toact in opposition to said bias means whereby said selected valve meansis opened in response to a predetermined value of fluid pressurecommunicated thereto, thereby permitting the exhausting of fluids fromsaid annular chamber on a selected side of said piston and whereby saidselected valve means is closed when the fluid pressure communicatedthereto falls below said predetermined value to prevent further movementof the piston within the annular chamber.

28. In an apparatus of the character set forth in claim 26 for movingpipe or rods into and out of a well, a hydraulic system for controllingreciprocal movements of said piston and piston rod slidably mounted insaid annular chamber and wherein the piston rod is secured to .one sideof the piston and slidably extends from one end of the annular chamberand said second pipe or rod gripping means is carried by said extendingend of said piston rod, said hydraulic system comprising: means forselectively communicating fluid pressure to the chamber portions definedby said annular chamber on opposite sides of said piston; means fortransferring fluid from one of said chamber portions to the other tocause movement of said piston within said annular chamber; and means forreceiving and storing the excess of fluid which is exhausted from thechamber portion on the side of said piston opposite said piston rod whenfluid is transferred therefrom to the other of said chamber portions.

29. In an apparatus of the character set forth in claim 26 for movingpipe or rods into and out of a well, a hydraulic system for controllingreciprocal movements of said piston and piston rod slidably mounted insaid annular chamber and wherein the piston rod is secured to one sideof the piston and slidably extends from one end of the annular chamberand said second gripping means is carried by said extending end of saidpiston rod, said hydraulic system comprising: means for selectivelycommunicating fluid pressure to the chamber portions defined by saidannular chamber on opposite sides of said piston; means for transferringfluid from one of said chamber portions to the other of said chamberportions to cause movement of said piston within said annular chamber;and means for supplying additional fluid to the chamber portion on theside of said piston opposite said piston rod when fluid is transferredthereto from the other of said chamber portions.

MP. A snubbing assembly adapted to be mounted sole- 1y on the wellheadfior controlling the movement of tubing under pressure in a wellcomprising: a seal assembly mounted on said wellhead having a boreextending therethrough and adapted to sealingly engage a length oftubing extending through said bore to confine the pressure of said well;first tubing gripping means having a bore extending therethrough andconnected to and supported on said seal assembly; said gripping meansbeing adapted to grip said length of tubing inserted in the bore thereofto hold the same against longitudinal movement; a pair of coaxialcylinders defining an annular chamber therebetween and connected to andsupported on said first gripping means, the inner one of said cylindershaving a bore extending therethnough; an annular piston slidably mountedin said annular chamber for longitudinal movement relative to saidcylinders; a tubular piston rod secured to said piston and disposedabout said inner cylinder in coaxial relation therewith and extendingupwardly out of the upper end of said annular chamber; second tubinggripping means mounted on the projecting end of said tubular piston rodremote from said wellhead; said second gripping means being adapted togrip said length of tubing inserted in the bore of said inner cylinder,all of said bores being aligned with the bore of said well to form apassage for said length of tubing; said first gripping means beingengaged with said tubing to hold and support the same againstlongitudinal movement while said second gripping means is disengagedtherefrom, and said second gripping means being engaged with said tubingfor gripping and moving the same longitudinally of said passage whensaid first gripping means is disengaged therefrom, whereby said tubingmay be moved longitudinally of said passage by said second grippingmeans; means communicating with said outer cylinder for applying fluidpressure against a selected side of said piston to impart movementthereto within said annular chamber whereby said length of tubinginserted within the bOI'e of said inner cylinder and gripped by saidsecond gripping means may be moved thnough said passage in a directiondetermined by the direction of movement imparted to said tubular pistonrod; and second means communicating with said :annular chamber forapplying fluid pressure against the side of said piston opposite saidselected side to impart movement thereto 29 in an opposite directionWithin said annular chamber to move said tubular piston rod and saidsecond gripping means in an opposite direction, whereby said length oftubing may be moved in said opposite direction.

31. An apparatus for moving elongate objects into and out of a wellpnovided with a wellhead and having an elongate object extendingtherethrough into said well, said apparatus including: an elongatehousing providing an elongate passage; means at the lower end of thehousing for connecting and supporting said housing solely on saidwellhead with said passage in alignment with the bore \of the well; aplurality of longitudinally spaced seal means carried by and secured tothe housing and movable into and out of sealing engagement with saidelongate object disposed in said passage to prevent fluid flow from thewell through the passage past said seal means externally of saidelongate object; a first gripping means carried by said housing abovesaid plurality of seal means for gripping said elongate object disposedin said passage to hold said object against longitudinal movement; asecond gripping means movably carried on said housing for gripping saidelongate object disposed in said passage, said second gripping meansbeing longitudinally spaced from and above said first gripping means andbeing movable relative thereto longitudinally of said housing; fluidpressure operated means supported by said housing and connected withsaid second gripping means for moving said second gripping meanslongitudinally of said housing relative to said first gripping means;said first gripping means being engaged wth said elongate object to holdand support the same against longitudinal movement while said secondgripping means is disengaged therefrom, and said second gripping meansbeing engaged with said elongate object for gripping and moving the samelongitudinally of the passage when said first gripping means isdisengaged therefrom, whereby said elongate object may be movedlongitudinally of said passage; and means for actuating said fluidpressure operated means for moving said second gripping meanslongitudinally of said housing, for actuating said seal means, and foractuating said gripping means, each independently of the other, wherebysaid seal means and said gripping means may be moved intoand out ofengagement with said elongate object disposed in said passage and saidmeans for moving said second gripping means longitudinally of saidhousing may be operated to move said gripping means so that saidelongate object may be moved longitudinally through said passage into orout of said well under pressure.

32. An apparatus for moving under pressure pipe or rods into and out ofa well provided with a wellhead and having a pipe or rod extendingthereinto, said apparatus including: a housing defining an elongatepassage; means at the lower end of the housing for connecting andsupporting said housing solely on a wellhead with said passage incommunication with the bore of the well; a plurality of longitudinallyspaced seal means carried by said housing for moving into and out ofsealing engagement with said pipe or rod when disposed in said passageto prevent fluid flow fnom the well through said passage past said sealmeans externally of said pipe or rod; a first gripping means carried bysaid housing for gripping said pipe or rod disposed in said passage tohold the same against longitudinal movement therein; a second grippingmeans for gripping said pipe or rod disposed in said passage, saidsecond gripping means being longitudinally spaced from said firstgripping means and movable longitudinally of said housing relativethereto; means supported by said housing for supporting and moving saidsecond gripping means relative to said first gripping means; said firstgripping means being engaged with said pipe or rod to hold and supportthe same against longitudinal movement while said second gripping meansis disengaged from said pipe or nod, and said second gripping meansbeing engaged with said pipe or rod for gripping and moving the samelongitudinally of the housing when said first gripping means isdisengaged from said pipe or rod, whereby said pipe or rod may be movedlongitudinally of said housing by said second gripping means; means foractuating said means for moving said second gripping means, foractuating said seal means, and for actuating said gripping means, eachindependently of the other, whereby said seal means and said grippingmeans may be moved into and out of engagement with said length of pipeor rod disposed in said passage and said means for moving said secondgripping means may be operated to move said second gripping means sothat said pipe or rod may be moved through said passage under pressureinto or out of said well; and a hydraulic system for controllingreciprocal movements of said means for moving said second gripping meansand including an annular cylinder and an elongate tubular pistonslidably mounted in said cylinder and having one end thereof extendingupwardly out :of said annular cylinder and connected with said secondgripping means, and system comprising: a source of fluid pressure;conduit means communicating said pressure to each side of the pistonwithin said cylinder; a first valve means in said conduit means operableto exhaust the fluid in said cylinder on one side of said piston; asecond valve means in said conduit means operable to exhaust the fluidin said cylinder on the other side of said piston; and means forcommunicating fluid pressure from said source to the one of said valvemeans which controls the exhaust of fluid from said cylinder on the sideof the piston opposite that to which fluid pressure is selectivelyapplied, said valve means being operable in response to a predeterminedfluid pressure communicated thereto from said source.

33. An apparatus for moving pipe or rods comprising: a pair of co-axialcylinders defining an annular chamber therebetween, the inner one ofsaid cylinders having a bore extending therethrough; an annular pistonslidably mounted in said annular chamber for longitudinal movementrelative to said cylinders; means for applying fluid pressure against aselected side of said piston to impart movement thereto within saidannular chamber; gripping means connected with said piston and operablefor gripping a pipe or rod disposed within said inner cylinder bore;fluid pressure operated means for moving said gripping means into andout of position for gripping said pipe or rod; elongate piston rod meansconnecting said gripping means and said piston whereby said grippingmeans is connected to said piston to move therewith whereby a length ofpipe or rod disposed in said bore may be moved therethrough in adirection determined by the direction of movement imparted to saidpiston; and seal means connected to the lower end of said co-axialcylinders below said gripping members and having a bore therethrough,and sealing members movable thereon between a position spaced from saidpipe or rod in a position sealing against said pipe or rod to preventfluid pressure passing in either direction longitudinally of said pipeor rod below said cylinders.

34. An apparatus for moving pipe or rod comprising: a pair of co-axialcylinders defining an annular chamber therebetween, the inner one ofsaid cylinders having a bore extending therethrough; an annular pistonslidably mounted in said annular chamber for longitudinal movementrelative to said cylinders; means for applying fluid pressure against aselected side of said piston to impart movement thereto within saidannular chamber; gripping means connected with said piston and operablefor gripping a pipe or rod disposed within said inner cylinder bore;fluid pressure operated means for moving sald gripping means into andout of position for gripping said pipe or rod; elongate piston rod meansconnecting said gripping means and said piston whereby said grippingmeans is connected to said piston to move therewith whereby a length ofpipe or rod disposed in said bore may be moved therethrough in adirection determined by the direction of movement imparted to saidpiston; 21 seal assembly connected to the lower end of said pair ofco-axial cylinders below said gripping members and having a boretherethrough and

3. A GRIPPING ASSEMBLY COMPRISING: A BODY HAVING A BORE EXTENDINGTHERETHROUGH: A PLURALITY OF GRIPPING MEANS MOVABLE ON SAID BODY BETWEENA RETRACTED POSITION AND AN INWARD OPERATIVE POSITION WHEREIN SAIDGRIPPING MEANS ARE ENGAGEABLE WITH AN ELONGATE MEMBER RECEIVED IN SAIDBORE TO GRIP SAID ELONGATE MEMBER; MEANS ON SAID BODY RESPONSIVE TOFLUID PRESSURE TO ALTERNATELY MOVE SAID GRIPPING MEANS BETWEEN SAIDRETRACTED AND SAID OPERATIVE POSITIONS; AND LOCKING MEANS ON SAID BODYENGAGEABLE WITH SAID MEANS FOR MOVING SAID GRIPPING MEANS BETWEENRETRACTED AND OPERATIVE POSITIONS FOR LOCKING SAID GRIPPING MEANS INSAID OPERATIVE POSITION.
 33. AN APPARATUS FOR MOVING PIPE OR RODSCOMPRISING: A PAIR OF CO-AXIAL CYLINDERS DEFINING AN ANNULAR CHAMBERTHEREBETWEEN, THE INNER ONE OF SAID CYLINDERS HAVING A BORE EXTENDINGTHERETHROUGH; AN ANNULAR PISTON SLIDABLY MOUNTED IN SAID ANNULAR CHAMBERFOR LONGITUDINAL MOVEMENT RELATIVE TO SAID CYLINDERS; MEANS FOR APPLYINGFLUID PRESSURE AGAINST A SELECTED SIDE OF SAID PISTON TO IMPART MOVEMENTTHERETO WITHIN SAID ANNULAR CHAMBER; GRIPPING MEANS CONNECTED WITH SAIDPISTON AND OPERABLE FOR GRIPPING A PIPE OR ROD DISPOSED WITHIN SAIDINNER CYLINDER BORE; FLUID PRESSURE OPERATED MEANS FOR MOVING SAIDGRIPPING MEANS INTO AND OUT OF POSITION FOR GRIPPING SAID PIPE OR ROD;ELONGATE PISON ROD MEANS CONNECTING SAID GRIPPING MEANS AND SAID PISTONWHEREBY SAID GRIPPING MEANS IS CONNECTED TO SAID PISTON TO MOVETHEREWITH WHEREBY A LENGTH OF PIPE OR ROD DISPOSED IN SAID BORE MAY BEMOVED THERETHROUGH IN A DIRECTION DETERMINED BY THE DIRECTION OFMOVEMENT IMPARTED TO SAID PISTON; AND SEAL MEANS CONNECTED TO THE LOWEREND OF SAID CO-AXIAL CYLINDERS BELOW SAID GRIPPING MEMBERS AND HAVING ABORE THERETHROUGH, AND SEALING MEMBERS MOVABLE THEREON BETWEEN APISITION SPACED FROM SAID PIPE OR ROD IN A POSITION SEALING AGAINST SAIDPIPE OR ROD TO PREVENT FLUID PRESSURE PASSING IN EITHER DIRECTIONLONGITUDINALLY OF SAID PIPE OR ROD BELOW SAID CYLINDERS.